Brief followup to the last post: via cshalizi's pinboard, here's an article that taught me something new about Columbine:
[In his book Columbine, author Dave] Cullen reconstructed the shooters' state of mind based on their own extensive written and filmed records and countless interviews with friends, family, and law enforcement. He concluded that Eric Harris was a psychopath, a young man without empathy or conscience, who coldly manipulated the deeply depressed Dylan Klebold into joining his scheme.
It was clear from the boys' meticulously documented plans that Columbine was an act of non-ideological domestic terrorism. Their goal was not merely to shoot bullies. They sought to first responders and parents with a mass shooting and then blow everyone up with huge bombs. Harris hoped this spectacular televised violence would touch of some sort of revolution. The bombs failed to detonate but the intent was clear.
If this is correct, then the Columbine shootings were in fact terrorism. It was violence staged against civilians specifically to generate an emotional reaction and an attendant policy reaction. However ill-conceived, weird, and amateurish, it appears to meet the definition.
Addendum: Incidentally this does not, of course, indicate that we should deal with terrorists of all types in the same way. The wall-to-wall media coverage of Columbine clearly played into the first half of the killers' plans. The most effective way to defeat this particular pair of terrorists would have been for the national media to ignore them entirely. The shooting should have been a purely local news story, focusing on memorializing the victims, and coverage of the killers should have been confined to wonky academic criminal science case studies.